Heretofore, chlorination of polyvinyl chloride resins has resulted in improved glass transition temperatures, reduced crystallinity, and enhanced combustion characteristics. However, the melt viscosity at processing temperatures was increased. Dynamic thermal stability, moreover, was generally undesirable for various processing areas such as calendering, sheet extrusion, and injection molding.
No prior art is known with regard to blends of CPVC which contain relatively high amounts, that is in excess of approximately 10 parts by weight per 100 parts by weight of the CPVC resin, of a processing stabilizing or a flow enhancing polymer such as alpha-methyl styrene. No literature, moreover, is known with regard to any unexpected improvements obtained by utilizing a flow enhancing polymer such as alpha-methyl styrene to yield improved processing stability, reduced melt viscosity, better sheet appearance and smoothness, and the like.